Data receiving method and apparatus supporting expansion modulation scheme

ABSTRACT

Provided are a data receiving method supporting an expansion modulation scheme and a wireless device using the same. The wireless device receives expansion sub-frame information indicating at least one expansion sub-frame supporting the expansion modulation scheme among a plurality of sub-frames and receives downlink data according to the expansion sub-frame information.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to wireless communications, and moreparticularly, to a data receiving method that supports higher modulationorder and a wireless device using the same in wireless communicationsystems.

2. Related Art

Long Term Evolution (LTE)/LTE-advanced (LTE-A) based on 3rd GenerationPartnership Project (3GPP) Technical Specification (TS) release 8-11 isa mobile communication standard which is widely used. Recently, the nextgeneration mobile communication that has higher efficiency is understandardization.

In order to cope with increasing data traffic, various techniques thatincrease transmission capacity of mobile communication systems have beenintroduced. For example, it has been considered that Multiple InputMultiple Output (MIMO) technique that uses multiple antennas, carrieraggregation technique that supports multiple cells, higher ordermodulation scheme, and so on.

It is required to consider the compatibility with scenarios undervarious conditions and legacy devices in introducing new techniques.

SUMMARY OF THE INVENTION

The present invention relates to a data receiving method that supportshigher modulation order and a wireless device using the same in wirelesscommunication systems.

In an aspect, a method for receiving data in a wireless communicationsystem is provided. The method includes receiving, by a wireless device,expansion subframe information indicating at least one expansionsubframe in which expansion modulation scheme is supported among aplurality of subframes, receiving, by the wireless device, downlinkcontrol information that includes a modulation and coding scheme (MCS)field indicating the expansion modulation scheme on a downlink controlchannel, in the at least one expansion subframe, and receiving, by thewireless device, downlink data on a downlink shared channel according tothe downlink control information.

The expansion subframe may support a modulation scheme that hasmodulation order of 8, and non-expansion subframe, which is not theexpansion subframe among the plurality of subframes, may support amodulation scheme that has a modulation order of less than 8.

The MCS field may have different bit numbers in the expansion subframeand the non-expansion subframe.

In another aspect, a wireless device in a wireless communication systemis provided. The wireless device includes a radio frequency (RF) unitconfigured to transmit and receive a radio signal, and a processorconnected to the RF unit. The processor is configured to receiveexpansion subframe information indicating at least one expansionsubframe in which expansion modulation scheme is supported among aplurality of subframes through the RF unit, receive downlink controlinformation that includes a modulation and coding scheme (MCS) fieldindicating the expansion modulation scheme on a downlink controlchannel, in the at least one expansion subframe through the RF unit, andreceive downlink data on a downlink shared channel according to thedownlink control information through the RF unit.

Higher data rate may be supported in various environments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a structure of a DL radio frame in 3GPP LTE.

FIG. 2 is an example of a subframe that has an EPDCCH.

FIG. 3 illustrates a communication method according to an embodiment ofthe present invention.

FIG. 4 illustrates a method for receiving data according to anembodiment of the present invention.

FIG. 5 is a block diagram illustrating a wireless communication systemin which the embodiment of the present invention is implemented.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A wireless device may be fixed or mobile, and may be referred to asanother terminology, such as a user equipment (UE), a mobile station(MS), a mobile terminal (MT), a user terminal (UT), a subscriber station(SS), a personal digital assistant (PDA), a wireless modem, a handhelddevice, etc. The wireless device may also be a device supporting onlydata communication such as a machine-type communication (MTC) device.

A base station (BS) is generally a fixed station that communicates withthe wireless device, and may be referred to as another terminology, suchas an evolved-NodeB (eNB), a base transceiver system (BTS), an accesspoint, etc.

Hereinafter, it is described that the present invention is appliedaccording to a 3rd generation partnership project (3GPP) long termevolution (LTE) based on 3GPP technical specification (TS) release 8 or3GPP LTE-advanced (LTE-A) based on 3GPP TS release 10. However, this isfor exemplary purposes only, and thus the present invention is alsoapplicable to various wireless communication networks. In the followingdescription, LTE and/or LTE-A are collectively referred to as LTE.

The wireless device may be served by a plurality of serving cells. Eachserving cell may be defined with a downlink (DL) component carrier (CC)or a pair of a DL CC and an uplink (UL) CC.

The serving cell may be classified into a primary cell and a secondarycell. The primary cell operates at a primary frequency, and is a celldesignated as the primary cell when an initial network entry process isperformed or when a network re-entry process starts or in a handoverprocess. The primary cell is also called a reference cell. The secondarycell operates at a secondary frequency. The secondary cell may beconfigured after an RRC connection is established, and may be used toprovide an additional radio resource. At least one primary cell isconfigured always. The secondary cell may be added/modified/released byusing higher-layer signaling (e.g., a radio resource control (RRC)message).

A cell index (CI) of the primary cell may be fixed. For example, alowest CI may be designated as the CI of the primary cell. It is assumedhereinafter that the CI of the primary cell is 0 and a CI of thesecondary cell is allocated sequentially starting from 1.

FIG. 1 illustrates a structure of a DL radio frame in 3GPP LTE. Thesection 6 of 3GPP TS 36.211 V10.2.0 (2011-06) “Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical Channels and Modulation(Release 10)” may be incorporated herein by reference.

A radio frame includes 10 subframes indexed with 0 to 9. One subframeincludes 2 consecutive slots. A time required for transmitting onesubframe is defined as a transmission time interval (TTI). For example,one subframe may have a length of 1 millisecond (ms), and one slot mayhave a length of 0.5 ms.

One slot may include a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in a time domain. Since the 3GPP LTE usesorthogonal frequency division multiple access (OFDMA) in a downlink(DL), the OFDM symbol is only for expressing one symbol period in thetime domain, and there is no limitation in multiple access schemes orterminologies. For example, the OFDM symbol may also be referred to asanother terminology such as a single carrier frequency division multipleaccess (SC-FDMA) symbol, a symbol period, etc.

Although it is described that one slot includes 7 OFDM symbols forexample, the number of OFDM symbols included in one slot may varydepending on a length of a cyclic prefix (CP). According to 3GPP TS36.211 V 10.2.0, in case of a normal CP, one slot includes 7 OFDMsymbols, and in case of an extended CR one slot includes 6 OFDM symbols.

A resource block (RB) is a resource allocation unit, and includes aplurality of subcarriers in one slot. For example, if one slot includes7 OFDM symbols in a time domain and the RB includes 12 subcarriers in afrequency domain, one RB can include 7×12 resource elements (REs).

A DL subframe is divided into a control region and a data region in thetime domain The control region includes up to first four OFDM symbols ofa first slot in the subframe. However, the number of OFDM symbolsincluded in the control region may vary. A physical downlink controlchannel (PDCCH) and other control channels are allocated to the controlregion, and a physical downlink shared channel (PDSCH) is allocated tothe data region.

As disclosed in 3GPP TS 36.211 V 10.2.0, examples of a physical controlchannel in 3GPP LTE/LTE-A include a physical downlink control channel(PDCCH), a physical control format indicator channel (PCFICH), and aphysical hybrid-ARQ indicator channel (PHICH).

The PCFICH transmitted in a first OFDM symbol of the subframe carries acontrol format indicator (CFI) regarding the number of OFDM symbols(i.e., a size of the control region) used for transmission of controlchannels in the subframe. A wireless device first receives the CFI onthe PCFICH, and thereafter monitors the PDCCH.

Unlike the PDCCH, the PCFICH does not use blind decoding, and istransmitted by using a fixed PCFICH resource of the subframe.

The PHICH carries a positive-acknowledgement(ACK)/negative-acknowledgement (NACK) signal for an uplink hybridautomatic repeat request (HARQ). The ACK/NACK signal for uplink (UL)data on a PUSCH transmitted by the wireless device is transmitted on thePHICH.

A physical broadcast channel (PBCH) is transmitted in first four OFDMsymbols in a second slot of a first subframe of a radio frame. The PBCHcarries system information necessary for communication between thewireless device and a BS. The system information transmitted through thePBCH is referred to as master information block (MIB). In comparisonthereto, system information transmitted on the PDCCH is referred to assystem information block (SIB).

Control information transmitted through the PDCCH is referred to asdownlink control information (DCI). The DCI may include resourceallocation of the PDSCH (this is referred to as a downlink (DL) grant),resource allocation of a PUSCH (this is referred to as an uplink (UL)grant), a set of transmit power control commands for individual UEs inany UE group, and/or activation of a voice over Internet protocol(VoIP).

In 3GPP LTE/LTE-A, transmission of a DL transport block is performed ina pair of the PDCCH and the PDSCH. Transmission of a UL transport blockis performed in a pair of the PDCCH and the PUSCH. For example, thewireless device receives the DL transport block on a PDSCH indicated bythe PDCCH. The wireless device receives a DL resource assignment on thePDCCH by monitoring the PDCCH in a DL subframe. The wireless devicereceives the DL transport block on a PDSCH indicated by the DL resourceassignment.

The 3GPP LTE uses blind decoding for PDCCH detection. The blind decodingis a scheme in which a desired identifier is de-masked from a cyclicredundancy check (CRC) of a received PDCCH (referred to as a candidatePDCCH) to determine whether the PDCCH is its own control channel byperforming CRC error checking.

A plurality of PDCCHs can be transmitted in one subframe. The wirelessdevice monitors the plurality of PDCCHs in every subframe. Monitoring isan operation of attempting PDCCH decoding by the wireless deviceaccording to a format of the monitored PDCCH.

The 3GPP LTE uses a search space to reduce a load of blind decoding. Thesearch space can also be called a monitoring set of a CCE for the PDCCH.The wireless device monitors the PDCCH in the search space.

The search space is classified into a common search space and aUE-specific search space. The common search space is a space forsearching for a PDCCH having common control information and consists of16 CCEs indexed with 0 to 15. The common search space supports a PDCCHhaving a CCE aggregation level of {4, 8}. However, a PDCCH (e.g., DCIformats 0, 1A) for carrying UE-specific information can also betransmitted in the common search space. The UE-specific search spacesupports a PDCCH having a CCE aggregation level of {1, 2, 4, 8}.

When a wireless device monitors the PDCCH based on C-RNTI, a DCI formatand a search space are determined depending on a transmission mode ofPDSCH. The following table shows examples of DCI format.

TABLE 1 DCI format Contents DCI format 0 Used in PUSCH scheduling DCIformat 1 Used in scheduling of one PDSCH codeword DCI format 1A Used incompact scheduling of one PDSCH codeword and random access process DCIformat 1B Used in compact scheduling of one PDSCH codeword havingprecoding information DCI format 1C Used in very compact scheduling ofone PDSCH codeword DCI format 1D Used in precoding and compactscheduling of one PDSCH codeword having power offset information DCIformat 2 Used in PDSCH scheduling of terminals configured in closed-loopspatial multiplexing mode DCI format 2A Used in PDSCH scheduling ofterminals configured in open-loop spatial multiplexing mode DCI format 3Used to transmit TPC command of PUCCH and PUSCH having 2 bit poweradjustments DCI format 3A Used to transmit TPC command of PUCCH andPUSCH having 1 bit power adjustment

The PDCCH is monitored in an area restricted to the control region inthe subframe, and a cell specific reference signal (CRS) which istransmitted through full band is used for demodulating the PDCCH. As atype of control data is diversified and an amount of control data isincreased, scheduling flexibility is decreased when using only theexisting PDCCH. In addition, in order to decrease an overhead caused byCRS transmission, an enhanced PDCCH (EPDCCH) is introduced.

FIG. 2 is an example of a subframe that has an EPDCCH.

The subframe may include zero or one PDCCH region 410 and zero or moreThe EPDCCH regions 420 and 430.

The EPDCCH regions 420 and 430 are regions in which a wireless devicemonitors the EPDCCH. The PDCCH region 410 is located in up to first fourOFDM symbols of the subframe, whereas the EPDCCH regions 420 and 430 maybe flexibly scheduled in an OFDM symbol located after the PDCCH region410.

One or more EPDCCH regions 420 and 430 may be assigned to the wirelessdevice. The wireless device may monitor EPDDCH data in the assignedEPDCCH regions 420 and 430.

The number/location/size of the EPDCCH regions 420 and 430 and/orinformation regarding a subframe for monitoring the EPDCCH may bereported by a BS to the wireless device by using a radio resourcecontrol (RRC) message or the like.

In the PDCCH region 410, a PDCCH may be demodulated on the basis of aCRS. In the EPDCCH regions 420 and 430, instead of the CRS, a DM-RS maybe defined for demodulation of the EPDCCH. An associated DM-RS may betransmitted in the EPDCCH regions 420 and 430.

In a carrier aggregation environment in which a plurality of servingcells is configured, there are two scheduling schemes of a cross carrierscheduling and a non-cross carrier scheduling. In the non-cross carrierscheduling, PDCCH-PDSCH scheduling is performed in one serving cell, andin the cross carrier scheduling, PDCCH-PDSCH scheduling is performed inserving cells different from each other. In the cross carrierscheduling, a serving cell in which the PDCCH/EPDCCH is received and aserving cell in which the PDSCH is scheduled may be different. A BS maynotify whether the cross carrier scheduling is set to a wireless device.When the cross carrier scheduling is set, a DCI on the PDCCH/EPDCCH mayinclude a carrier indicator field (CIF) that indicates a serving cell inwhich the PDSCH is scheduled. A cell in which the PDCCH/EPDCCH isscheduled is referred to a scheduling cell, and a cell in which thePDSCH is scheduled is referred to a scheduled cell.

Below are contents of Channel state information (CSI) reference signal(RS) that are extracted from 3GPP TS 36.211 V11.2.0 (2013-02), which isa reference of the present invention.

Start

Multiple CSI reference signal configurations can be used in a givencell. A UE can be configured with multiple sets of CSI referencesignals,

up to three configurations for which the UE shall assume non-zerotransmission power for the CSI-RS, and

zero or more configurations for which the UE shall assume zerotransmission power.

The CSI-RS configurations for which the UE shall assume non-zerotransmission power are provided by higher layers.

The CSI-RS configurations for which the UE shall assume zerotransmission power in a subframe are given by a bitmap derived accordingto Section 7.2.7 in [4]. For each bit set to one in the 16-bit bitmap,the UE shall assume zero transmission power for the resource elementscorresponding to the four CSI reference signal column in Tables6.10.5.2-1 and 6.10.5.2-2 for normal and extended cyclic prefix,respectively, except for resource elements that overlap with those forwhich the UE shall assume non-zero transmission power CSI-RS asconfigured by higher layers. The most significant bit corresponds to thelowest CSI reference signal configuration index and subsequent bits inthe bitmap correspond to configurations with indices in increasingorder.

CSI reference signals can only occur in

downlink slots where ns mode 2 fulfills the condition in Tables6.10.5.2-1 and 6.10.5.2-2 for normal and extended cyclic prefix,respectively, and

where the subframe number fulfills the conditions in Section 6.10.5.3.

The UE shall assume that CSI reference signals are not transmitted

in the special subframe(s) in case of frame structure type 2,

-   -   in subframes where transmission of a CSI-RS would collide with        transmission of synchronization signals, PBCH, or        SystemInformationBlockType1 messages,

in the primary cell in subframes configured for transmission of pagingmessages in the primary cell for any UE with the cell-specific pagingconfiguration.

End

Below are a part of sections 7.1.9, 7.1.10 and 7.2 that are extractedfrom 3GPP TS 36.213 V11.1.0 (2012-12), which is a reference of thepresent invention.

Start

7.1.9 PDSCH resource mapping parameters

A UE configured in transmission mode 10 for a given serving cell can beconfigured with up to 4 parameter sets by higher layer signaling todecode PDSCH according to a detected PDCCH/EPDCCH with DCI format 2Dintended for the UE and the given serving cell. The UE shall use theparameter set according to the value of the ‘PDSCH RE Mapping andQuasi-Co-Location indicator’ field (mapping defined in Table 7.1.9-1) inthe detected PDCCH/EPDCCH with DCI format 2D for determining the PDSCHRE mapping (defined in Section 6.3.5 of [3]) and PDSCH antenna portquasi co-location (defined in Section 7.1.10). For PDSCH without acorresponding PDCCH, the UE shall use the parameter set indicated in thePDCCH/EPDCCH with DCI format 2D corresponding to the associated SPSactivation for determining the PDSCH RE mapping (defined in Section6.3.5 of [3]) and PDSCH antenna port quasi co-location (defined inSection 7.1.10).

The following parameters for determining PDSCH RE mapping and PDSCHantenna port quasi co-location are configured via higher layer signalingfor each parameter set:

‘Number of CRS antenna ports for PDSCH RE mapping’.

‘CRS frequency shift for PDSCH RE mapping’.

‘MBSFN subframe configuration for PDSCH RE mapping’.

‘Zero-power CSI-RS resource configuration for PDSCH RE mapping’.

‘PDSCH starting position for PDSCH RE mapping’.

‘CSI-RS resource configuration identity for PDSCH RE mapping’.

A UE configured in transmission mode 10 for a given serving cell can beconfigured with a parameter set selected from the four parameter sets inTable 7.1.9-1 by higher layer signaling for determining the PDSCH REmapping (defined in Section 6.3.5 of [3]) and PDSCH antenna port quasico-location (defined in Section 7.1.10) to decode PDSCH according to adetected PDCCH/EPDCCH with DCI format 1A intended for the UE and thegiven serving cell. The UE shall use the configured parameter set,determining the PDSCH RE mapping (defined in Section 6.3.5 of [3]) andPDSCH antenna port quasi co-location (defined in Section 7.1.10) fordecoding PDSCH corresponding to detected PDCCH/EPDCCH with DCI format 1Aand PDSCH without a corresponding PDCCH associated with SPS activationindicated in PDCCH/EPDCCH with DCI format 1A.

7.1.10 Antenna ports quasi co-location for PDSCH

A UE configured in transmission mode 1-10 may assume the antenna ports0-3 of a serving cell are quasi co-located (as defined in [3]) withrespect to delay spread, Doppler spread, Doppler shift, average gain,and average delay.

A UE configured in transmission mode 8-10 may assume the antenna ports7-14 of a serving cell are quasi co-located (as defined in [3]) for agiven subframe with respect to delay spread, Doppler spread, Dopplershift, average gain, and average delay.

A UE configured in transmission mode 1-9 may assume the antenna ports0-3, 5, 7-22 of a serving cell are quasi co-located (as defined in [3])with respect to Doppler shift, Doppler spread, average delay, and delayspread.

A UE configured in transmission mode 10 is configured with one of twoquasi co-location types by higher layer signaling to decode PDSCHaccording to transmission scheme associated with antenna ports 7-14:

Type A: The UE may assume the antenna ports 0-3, 7-22 of a serving cellare quasi co-located (as defined in [3]) with respect to delay spread,Doppler spread, Doppler shift, and average delay

Type B: The UE may assume the antenna ports 15-22 corresponding to theCSI-RS resource configuration identified by ‘CSI-RS resourceconfiguration identity for PDSCH RE mapping’ in Section 7.1.9 and theantenna ports 7-14 associated with the PDSCH are quasi co-located (asdefined in [3]) with respect to Doppler shift, Doppler spread, averagedelay, and delay spread.

7.2 UE procedure for reporting Channel State Information (CSI)

The time and frequency resources that can be used by the UE to reportCSI which consists of channel quality indicator (CQI), precoding matrixindicator (PMI), precoding type indicator (PTI), and/or rank indication(RI) are controlled by the eNB. For spatial multiplexing, as given in[3], the UE shall determine a RI corresponding to the number of usefultransmission layers. For transmit diversity as given in [3], RI is equalto one.

A UE in transmission mode 8 or 9 is configured with or without PMI/RIreporting by the higher layer parameter pmi-RI-Report.

A UE in transmission mode 10 can be configured with one or more CSIprocesses per serving cell by higher layers. Each CSI process isassociated with a CSI-RS resource (defined in Section 7.2.5) and aCSI-interference measurement (CSI-IM) resource (defined in Section7.2.6). A CSI reported by the UE corresponds to a CSI process configuredby higher layers. Each CSI process can be configured with or withoutPMI/RI reporting by higher layer signaling.

A UE is configured with resource-restricted CSI measurements if thesubframe sets CCSI,0 and CCSI,1 are configured by higher layers.

CSI reporting is periodic or aperiodic.

If the UE is configured with more than one serving cell, it transmitsCSI for activated serving cell(s) only.

If a UE is not configured for simultaneous PUSCH and PUCCH transmission,it shall transmit periodic CSI reporting on PUCCH as defined hereafterin subframes with no PUSCH allocation.

If a UE is not configured for simultaneous PUSCH and PUCCH transmission,it shall transmit periodic CSI reporting on PUSCH of the serving cellwith smallest ServCelllndex as defined hereafter in subframes with aPUSCH allocation, where the UE shall use the same PUCCH-based periodicCSI reporting format on PUSCH.

A UE shall transmit aperiodic CSI reporting on PUSCH if the conditionsspecified hereafter are met. For aperiodic CQI/PMI reporting, RIreporting is transmitted only if the configured CSI feedback typesupports RI reporting.

For serving cell c, a UE configured in transmission mode 10 with PMI/RIreporting for a CSI process can be configured with a ‘RI-reference CSIprocess’. If the UE is configured with a ‘RI-reference CSI process’ forthe CSI process, the reported RI for the CSI process shall be the sameas the reported RI for the configured ‘RI-reference CSI process’. The UEis not expected to receive an aperiodic CSI report request for a givensubframe triggering a CSI report including CSI associated with the CSIprocess and not including CSI associated with the configured‘RI-reference CSI process’.

For a UE in transmission mode 10, in case of collision between CSIreports of same serving cell with PUCCH reporting type of the samepriority, and the CSI reports corresponding to different CSI processes,the CSI reports corresponding to all CSI processes except the CSIprocess with the lowest CSIProcessIndex are dropped.

If the UE is configured with more than one serving cell, the UEtransmits a CSI report of only one serving cell in any given subframe.For a given subframe, in case of collision of a CSI report with PUCCHreporting type 3, 5, 6, or 2 a of one serving cell with a CSI reportwith PUCCH reporting type 1, 1 a, 2, 2 b, 2 c, or 4 of another servingcell, the latter CSI with PUCCH reporting type (1, 1 a, 2, 2 b, 2 c, or4) has lower priority and is dropped. For a given subframe, in case ofcollision of CSI report with PUCCH reporting type 2, 2 b, 2 c, or 4 ofone serving cell with CSI report with PUCCH reporting type 1 or 1 a ofanother serving cell, the latter CSI report with PUCCH reporting type 1,or 1 a has lower priority and is dropped.

For a given subframe and UE in transmission mode 1-9, in case ofcollision between CSI reports of different serving cells with PUCCHreporting type of the same priority, the CSI of the serving cell withlowest ServCelllndex is reported, and CSI of all other serving cells aredropped.

For a given subframe and UE in transmission mode 10, in case ofcollision between CSI reports of different serving cells with PUCCHreporting type of the same priority and the CSI reports corresponding toCSI processes with same CSIProcessIndex, the CSI reports of all servingcells except the serving cell with lowest ServCelllndex are dropped.

For a given subframe and UE in transmission mode 10, in case ofcollision between CSI reports of different serving cells with PUCCHreporting type of the same priority and the CSI reports corresponding toCSI processes with different CSIProcessIndex, the CSI reports of allserving cells except the serving cell with CSI reports corresponding toCSI process with the lowest CSIProcessIndex are dropped.

End

Hereinafter, a method for supporting an expansion modulation schemewhich is proposed will be described.

3GPP LTE supports a modulation order of maximum 6, and modulationschemes of quadrature phase shift keying (QPSK), 16-quadrature amplitudemodulation (QAM), and 64-QAM.

However, it has been considered to support modulation orders of 7 orhigher (e.g., 128-QAM, 256-QAM, 1024-QAM, etc.) in order to improve thefrequency efficiency. Hereinafter, the modulation scheme that has ahigher modulation order than that of the modulation scheme which issupported in 3GPP LTE is referred to the expansion modulation scheme.

FIG. 3 illustrates a communication method according to an embodiment ofthe present invention.

In step S310, a BS sends a support message that notifies whether theexpansion modulation scheme is used to a wireless device. The supportmessage may be transmitted via system information or an RRC message. Thesupport message may include information on whether the expansionmodulation scheme is supported and information on period/resourcesupported by the expansion modulation scheme.

In step S320, the wireless device sends a capability message thatnotifies that the wireless device is available to support the expansionmodulation scheme to the BS.

The expansion modulation scheme may be supported for each frequency bandor each frequency band group. Otherwise, the expansion modulation schememay be supported for each frequency resource or each RB. When aplurality of frequency bands is configured, the expansion modulationscheme may be supported for each or a combination of the plurality offrequency bands. The support message or the capability message mayinclude the information on a frequency band (or a combination offrequency bands) in which the expansion modulation scheme is supported.

The expansion modulation scheme may be supported per each serving cell.For example, although a primary cell does not support the expansionmodulation scheme, one of secondary cells may support the expansionmodulation scheme. When the primary cell configures the secondary cell,the primary cell may notify whether the corresponding secondary cellsupports the expansion modulation scheme to the wireless device.

When the cross carrier scheduling is configured, if the scheduled cellsupports the expansion modulation scheme, the corresponding DCI mayinclude the information on the expansion modulation scheme, even thoughthe scheduled cell does not support the expansion modulation scheme.

If the primary cell supports the expansion modulation scheme, thesecondary cell may be defined to support the expansion modulation schemewithout any separate configuration.

When the expansion modulation scheme is configured, it becomesproblematic to use the channel quality indicator (CQI) table to whichmodulation and coding scheme (MCS) table is related for the CQI report.That is whether a legacy CQI table related to a legacy MCS table inwhich the expansion modulation scheme is not considered is utilized oran expansion CQI table related to an expansion MCS table in which theexpansion modulation scheme is considered is utilized. The expansion MCStable may include a MCS table that has an index indicating the expansionmodulation scheme (e.g., 256-QAM) in addition to the existing modulationscheme. Furthermore, the expansion CQI table may include a CQI tablethat has an index indicating the expansion modulation scheme (e.g.,256-QAM) in addition to the existing modulation scheme. If the expansionmodulation scheme is configured, the wireless device may configure theexpansion CQI table related to the expansion MCS table to use for theCQI report. In another embodiment, the BS may notify whether theexpansion MCS table is used to the wireless device separately fromwhether the expansion modulation scheme is supported. In other words,although the BS itself does not support the expansion modulation scheme,the BS may configure whether to use the expansion MCS/CQI table to thewireless device. This may be used for another BS to use the expansionmodulation scheme in case that any one BS does not support the expansionmodulation scheme in a situation that BSs are required to cooperate suchas the CoMP. The wireless device may report the channel qualityindicator of 4 bits or 5 bits. The bit number of CQI may be determinedaccording to a duplex mode of the corresponding cell. For example, afrequency division duplex (FDD) cell that supports FDD may use the CQIof 5 bits. A time division duplex (TDD) cell that supports TDD may usethe CQI of 4 bits. In case of the TDD cell, the expansion MCS table maynot be used, and in case of the FDD cell, the expansion MCS table may beused.

A dual connectivity environment refers to a case in which a plurality ofaccesses (e.g. a first access is a macro cell and a second access is amicro cell) is configured. In this case, each access is performed ineach cell independently, which is different from the CA in which aconfiguration of a secondary cell is performed by a primary cell.Whether to support the expansion modulation scheme may be notified tothe wireless device for each access. If the dual connectivity and the CAare simultaneously configured, the method described above may be appliedto a cell for the CA.

Now, the support of the expansion modulation scheme in the CoMPenvironment will be described.

Hereinafter, the CoMP means cooperation between transmission points(TPs) that are geographically remote. The set of TPs that participate ina data transmission to the wireless device refers to a CoMP set.

Whether to support the expansion modulation scheme and/or whether to usethe expansion MCS table may be notified to the wireless device for eachTP.

When a CoMP operation is configured to the wireless device, a pluralityof TPs may be configured. Whether the expansion modulation scheme issupported may be notified to the wireless device for each TP. Dependingon whether the expansion modulation scheme is supported, a bit number ofMCS fields in DCI may be changed. For example, if the expansionmodulation scheme is supported, MCS fields of 6 bits are used, and ifthe expansion modulation scheme is not supported, MCS fields of 5 bitsmay be used.

In case of the PDCCH, a bit number of MCS fields may be determineddepending on whether the expansion modulation scheme is supported in aserving cell (e.g. a scheduled cell). For example, if a serving cellsupports the expansion modulation scheme, MCS fields of 6 bits may beused, and if a serving cell does not support the expansion modulationscheme, MCS fields of 5 bits may be used. The same rule may be appliedto the MCS table for the CQI report. If a serving cell supports theexpansion modulation scheme regardless of a TP, the wireless device mayassume that all TPs use the MCS table that has the expansion modulationscheme.

In case of the EPDCCH, whether to use the MCS field/MCS table thatsupports the expansion modulation scheme may be configured by a PDSCHremapping and quasi co-location indicator (PQI) which is related to thecorresponding EPDCCH set. For example, if the first entry of a PQI tableis related to a first EPDCCH set and the first entry instructs to usethe expansion MCS table, the wireless device may expect that DCI of thecorresponding EPDCCH set supports the expansion modulation scheme. Ifthere is an ambiguity among a plurality of EPDCCH sets, the wirelessdevice may follow the set of the first EPDCCH set. If the first EPDCCHset supports the expansion modulation scheme, the wireless device mayassume that the remaining EPDCCH sets also support the expansionmodulation scheme. The DCI format on the EPDCCH is DCI format 1×/2y.Since DCI format 1A is used only for a legacy device, if a use of theexpansion modulation scheme is configured, it may be expected that theMCS field including the expansion modulation scheme may be used in DCIformats except DCI format 1A.

Whether to support the expansion modulation scheme may be dynamicallydetermined for each PDSCH. When transmission mode 10 is used in 3GPPLTE, DCI format 2D has the PQI of 2 bits. This means that the PQI hasfour PQI entries. When it is assumed that a PQI entry indicates whetherto support the expansion modulation scheme, it may be assumed that thecorresponding PQI entry indicates whether a PDSCH supports the expansionmodulation scheme. For example, if the related PQI entry supports theexpansion modulation scheme, it may be interpreted that the MCS of ascheduled PDSCH is based on the MCS table that supports the expansionmodulation scheme. This may be interpreted that whether to support theexpansion modulation scheme may be signaled through the PQI entry. If aconfiguration of the expansion modulation scheme is given bynon-zero-power (NZP) channel state information (CSI)-reference signal(RS) configuration, the wireless device may determine whether theexpansion modulation scheme is supported using the NZP CSI-RSconfiguration in the PQI entry. According to a CSI configuration relatedto the corresponding NZP CSI-RS configuration, whether the expansion MCStable is used may also be determined This means which MCS table(expansion or legacy) is to be used may be configured when configuringthe CSI.

When the wireless device is configured with transmission mode 10 and DCIformat 1A is used, the following matters may be considered. Hereinafter,it is assumed that the first PQI entry indicates whether the expansionmodulation scheme is supported.

A. Regardless of whether the corresponding subframe ismulticast-broadcast single-frequency network (MBSFN) subframe ornon-MBSFN subframe, DCI format 1A uses the legacy MCS table. Regardlessof the indication of the first PQI entry, the wireless device may ignorethe support of the expansion modulation scheme in DCI format 1A.

B. MBSFN subframe follows an instruction of the first PQI entry, andnon-MBSFN subframe ignores the support of the expansion modulationscheme.

C. If DCI format 1A is scheduled in a common search space, the supportof the expansion modulation scheme is ignored (i.e., use the legacy MCStable). Otherwise, an instruction of the first PQI table is followed.

D. If DCI format 1A is scheduled in a common search space, the supportof the expansion modulation scheme is ignored. Otherwise, MBSFN subframefollows an instruction of the first PQI entry, and non-MBSFN subframeignores the support of the expansion modulation scheme.

E. According to 3GPP TS 36.213, type A and type B are defined for quasico-location (QCL) operation in transmission mode 10. If the wirelessdevice is configured with QCL type A, the support of the expansionmodulation scheme is ignored. If the wireless device is configured withQCL type B, one of the methods B, C and D may be followed. During an RRCreconfiguration operation, it is assumed that the QCL operation isaccording to QCL type A. Accordingly, if the first PQI entry indicatesthe support of the expansion modulation scheme and is configured tofollow an instruction of the first PQI entry for DCI format 1A of theMBSFN subframe, the wireless device may not expect to receive DCI format1A in the MBSFN subframe during the RRC reconfiguration operation.

The proposed method may also applied to other DCI format similar to DCIformat 2D. For example, if the wireless device is configured with QCLtype A, the wireless device may use the same configuration for theexpansion modulation scheme for all TPs (or all serving cells). The RRCconfiguration or the first NZP CSI-RS index may be used in order toactivate the expansion modulation scheme. The configuration of theexpansion modulation scheme may be given only for the case that QCL typeB is configured to the wireless device. If QCL type A is configured, thewireless device may ignore the configuration of the expansion modulationscheme. When the configuration of the expansion modulation scheme is notgiven, the RRC configuration may be used as a default configuration. Ifthe expansion MCS table is configured for each PQI entry and QCL type Ais configured, the wireless device may follow an instruction of thefirst PQI entry. During the CSI process, the wireless device may followthe CSI configuration for the expansion modulation scheme. If QCL type Ais configured, the wireless device may apply the MCS table determinationfor the CQI report to the NZP CSI-RS configuration. That is, the MCStable for the PDSCH may be determined based on the PQI entry, and theMCS table for the CQI table may be determined based on the ZP CSI-RSconfiguration.

The semi-persistent scheduling (SPS) may also support the expansionmodulation scheme. If the expansion modulation scheme is configured,higher modulation order (e.g., 256-QAM) may be applied to an SPStransmission.

Whether to support the expansion modulation scheme may be given by aspecific indicator (e.g., PQI entry), and the specific indicator mayindicate at least one of the followings: (1) Whether the TP supports theexpansion modulation scheme, (2) whether the MCS field in DCI supportsthe expansion modulation scheme, and (3) whether the expansion MCS tableis used for the CQI report.

For the CSI report, the same rule may be used for calculating CQI. Forexample, for each CSI process related to the CSI-RS resource, whetherthe CQI is determined based on the expansion CQI table or the legacy CQItable may be configured. For each CSI process, whether the expansionmodulation scheme is supported may be configured. When the expansion CQItable is used for the CQI report, a bit number for the CQI report may bedetermined based on a CP length of the configured CSI-RS resource. Ifthe CSI process of a TP that has normal CP is configured to support theexpansion modulation scheme, the CQI of 5 bits may be reported.Otherwise, the CQI of 4 bits may be reported. Even though TPs of duplexmodes different from each other is configured for the CQI report for aCoMP operation, the rules same as the case of the CA may be applied. Forexample, a TDD TP may use the CQI based on the legacy CQI table alwaysregardless of whether the expansion modulation scheme is supported.

The above described embodiment may be applied to any cases of an idealbackhaul or a non-ideal backhaul in the CoMP operation.

An enhanced interference mitigation and traffic adaptation (eIMTA) is atechnique that efficiently improves traffic load and interferencemitigation by dynamically changing a UL-DL configuration in TDD.Configuration of the eIMTA means that the BS may dynamically change aUL-DL configuration shown in the table below or may change a UL-DLconfiguration shown in the table below into an arbitrary UL-DLconfiguration to the wireless device.

TABLE 2 UL-DL Config- Switch-point Subframe index uration periodicity 01 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5 ms D S U U D D S U U D2 5 ms D S U D D D S U D D 3 10 ms  D S U U U D D D D D 4 10 ms  D S U UD D D D D D 5 10 ms  D S U D D D D D D D 6 5 ms D S U U U D S U U D

In the table above, ‘D’ represents a DL subframe, ‘U’ represents a ULsubframe and ‘S’ represents an S subframe. S subframe may also berepresented as a DL subframe. If the wireless device receives a UL-DLconfiguration from the BS, the wireless device may detect which frame isthe DL subframe or the UL subframe according to a configuration of radioframe.

The change of UL-DL configuration may be performed through systeminformation (e.g., master information block (MIB) or system informationblock (SIB)), an RRC message or DCI. The DL subframes that are notchangeable through configurations, that is, entirely fixed to DL arereferred to fixed DL subframes, and the DL subframes that are changeablethrough configurations and accordingly, in which DL/UL subframes arecoexisted with respect to neighboring cells are referred to flexible DLsubframes. That is, in the flexible DL subframes, although a specificcell may be a DL subframe, another cell may be a UL subframe. Otherwise,in the flexible DL subframes, although it may be a DL subframe on amoment, it may be a UL subframe in other times.

For a wireless device to which the eIMTA is configured, whether tosupport the expansion modulation scheme may be given as follows.

(1) Regardless of DL-UL configurations, once the expansion modulationscheme is configured, all DL subframes support the expansion modulationscheme.

(2) According to DL-UL configurations, only fixed DL subframes or Ssubframe supports the expansion modulation scheme.

(3) For the flexible DL subframes, whether to support the expansionmodulation scheme is separately configured.

Owing to UL transmissions of neighboring devices, the flexible DLsubframes have higher interference level in comparison with the fixed DLsubframes. Accordingly, it may be beneficial to inactivate the expansionmodulation scheme to the flexible DL subframes. For each subframe type,whether to support the expansion modulation scheme may be configured.For each subframe type, the MCS and/or CQI tables different from eachother may be configured.

When the MCS tables (or the CQI tables) different from each other areused, a differential CQI may be considered. For example, in periodic CQIreport, in case that each measurement set is configured in 200 mswindow, the CQI may be calculated for each measurement set. Sinceinterference conditions undergone for each measurement set aredifferent, it may be efficient to have the MCS and/or CQI tablesdifferent from each other for each measurement set. Considering theeIMTA and/or an enhanced inter-cell interference coordination (eICIC)and/or a dynamic interference condition, different MCS and/or CQI tablesmay be configured for each subframe set.

Whether to use the expansion MCS table may be determined based on a ULsubframe set. For example, a UL subframe set that has betterinterference condition uses the CQI of 5 bits (i.e., the expansion MCStable may be applied). A UL subframe that has not good interferencecondition uses the CQI of 4 bits (i.e., the legacy MCS table may beapplied).

If an FDD UL band is used for a DL transmission of a small cell, theapplication of the expansion modulation scheme in the UL band may belimited due to high interference level caused by a UL transmission. Inthis case, separate signaling may be required for the application of theexpansion modulation scheme. Separate CSI measurement set may beconfigured for a DL transmission in the UL band, and whether to supportthe expansion modulation scheme may be notified to the CSI measurementset.

FIG. 4 illustrates a method for receiving data according to anembodiment of the present invention. This method may be performed afterthe embodiment of FIG. 3 is performed.

In step S410, a BS sends the expansion subframe information to awireless device. The expansion subframe information includes informationon a subframe or subframe set in which the expansion modulation schemeis supported. The expansion subframe refers to a subframe in which theexpansion modulation scheme is supported, and non-expansion subframerefers to a legacy subframe in which the expansion modulation scheme isnot supported.

For each of a plurality of subframe sets, the support of the expansionmodulation scheme may be configured. For example, for each of the fixedsubframe set and the flexible subframe set of the eIMTA, whether tosupport the expansion modulation scheme may be configured. Otherwise,whether to support the expansion modulation scheme may be configured foreach measurement set. Or, for each of the MBSFN subframe set and/or thenon-MBSFN subframe, whether to support the expansion modulation schememay be configured.

Although the support of the expansion modulation scheme is available, ifseparate subframe set is not given, the wireless device may expect thatthe expansion modulation scheme is supported for all subframes. Ifseparate subframe set available to support the expansion modulationscheme is given, the wireless device may expect that the expansionmodulation scheme is supported for the corresponding subframe set.

For transmission modes 1 to 9, one MCS and/or CQI table may beconfigured for each measurement set. If the expansion MCS and/or CQItable is configured for one measurement set, the wireless device mayassume that the expansion modulation scheme is also supported for thesubframe that is not belonged to the one measurement set. Otherwise, thewireless device may assume that the expansion modulation scheme is notsupported for the subframe that is not belonged to the one measurementset.

In more particular, for transmission modes 1 to 9, one CQI table may beconfigured for each measurement set. If the expansion CQI table isconfigured for one measurement set, the wireless device may assume thatthe expansion modulation scheme is also supported for the subframe thatis not belonged to the one measurement set. Otherwise, the wirelessdevice may assume that the expansion modulation scheme is not supportedfor the subframe that is not belonged to the one measurement set. Inmore particular, for transmission modes 1 to 9, one CQI table may beconfigured for each measurement set. If the expansion CQI table isconfigured for one measurement set, the wireless device may assume thatthe expansion modulation scheme is applied to all subframes for a DLtransmission.

Or, differently, in transmission modes 1 to 9, one MCS table may beconfigured for each subframe measurement set. This MCS table maycorrespond to the CQI table for the same subframe set. If at least onesubframe measurement set is configured to have the expansion modulationscheme, the expansion MCS table and/or the expansion CQI table may beused for the subframe that is belonged to each subframe set. If at leastone subframe measurement set is configured not to have the expansionmodulation scheme, a use of the legacy MCS table and/or the legacy CQItable may be regarded for the subframe that is belonged to each subframeset.

In step S420, the wireless device receives the PDSCH to which theexpansion modulation scheme is applied in an expansion subframe.

Now, the application of the expansion modulation scheme in a hybridautomatic repeat request (HARQ) will be described.

For the HARQ that has the same HARQ process number, the support of theexpansion modulation scheme may be maintained. If the expansionmodulation scheme is supported in an initial transmission, the expansionmodulation scheme is also supported in a retransmission. Accordingly,whether the expansion modulation scheme is supported in a retransmissionmay be determined depending on whether the expansion modulation schemeis supported in an initial transmission. Whether the expansion MCS tableis used in a retransmission is determined depending on whether theexpansion MCS table is used in an initial transmission.

In an SPS transmission, the support of the expansion modulation schememay be maintained depending on whether the expansion modulation schemeis supported in an SPS allocation which is the most recently allocated.If the most recent SPS allocation supports the expansion modulationscheme, the later SPS transmission may also support the expansionmodulation scheme.

The table below is an MCS table which is used for a PDSCH allocationwithin DCI, in 3GPP LTE. The DCI has MCS fields of 5 bits.

TABLE 3 MCS index Modulation order 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 92 10 4 11 4 12 4 13 4 14 4 15 4 16 4 17 6 18 6 19 6 20 6 21 6 22 6 23 624 6 25 6 26 6 27 6 28 6 29 2 30 4 31 6

If the MCS table is reused for the expansion modulation scheme and MCSfields are 5 bits, there is no ambiguity in DCI interpretation. Forthis, it may be implemented that at least one of MCS indexes 0 to 31indicates modulation order 8. For example, it may be implemented thatMCS index 31 or 39 indicates modulation order 8.

Optionally, a specific MCS index may indicate different modulationorders depending on whether the expansion modulation scheme issupported. For example, MCS indexes 29 to 31 in Table 3 above may beconfigured as follows. MCS indexes and modulation order are shown justfor example.

TABLE 4 MCS index 256-QAM is not supported 256-QAM is supported 29 2 430 4 6 31 6 8

If an initial transmission in which 256-QAM is supported is started, inthe later retransmission, MCS indexes 29 to 31 may also be interpretedas modulation order 4, 6 and 8, respectively. If an initial transmissionin which 256-QAM is not supported is started, in the laterretransmission, MCS indexes 29 to 31 may also be interpreted asmodulation order 2, 4 and 6, respectively. If one of MCS indexes 0 to 28is used in an initial transmission but whether the expansion modulationscheme is supported is not separately configured, it becomes problematicwhich MCS table is used in retransmission. So far as not beingseparately designated, in retransmission, MCS indexes 29 to 31 may beinterpreted as modulation order 2, 4 and 6, respectively, similar to theconventional case.

An MCS index that indicates the expansion modulation scheme may be addedto the MCS table, and MCS fields may be configured as 6 bits. This meansthat a bit number of MCS fields within DCI is changed depending onwhether to support the expansion modulation scheme. If a subframesupports the expansion modulation scheme, the DCI monitored in thecorresponding subframe may be configured to have MCS fields of 6 bits.

Now, the eIMTA will be considered together with a retransmission. If theexpansion modulation scheme is supported and MCS fields of 6 bits areused, the expansion modulation scheme may be used in all subframes (orall expansion subframes). If MCS fields of 5 bits are used forsupporting the expansion modulation scheme, the MCS fields may beinterpreted according to a HARQ process number and/or a new dataindicator (NDI). In non-MBSFN subframe, it may be implemented that DCIformat 1A supports only the legacy MCS table such that low SINR range isincreased and large packet size is supported.

FIG. 5 is a block diagram showing wireless communication system toimplement an embodiment of the present invention.

A BS 50 includes a processor 51, a memory 52 and a radio frequency (RF)unit 53. The memory 52 is operatively coupled with the processor 51 andstores a variety of commands to operate the processor 51. The RF unit 53is operatively coupled with the processor 51, and transmits and/orreceives a radio signal. The processor 51 is configured to implementproposed functions, procedures and/or methods described in thisdescription. In the embodiments of FIG. 3 and FIG. 4 described above, anoperation of the BS 50 may be implemented by the processor 51.

A wireless device 60 includes a processor 61, a memory 62 and a RF unit63. The memory 62 is operatively coupled with the processor 61 andstores a variety of commands to operate the processor 61. The RF unit 63is operatively coupled with the processor 61, and transmits and/orreceives a radio signal. The processor 61 is configured to implementproposed functions, procedures and/or methods described in thisdescription. In the embodiments of FIG. 3 and FIG. 4 described above, anoperation of the wireless device 60 may be implemented by the processor61.

The processor may include application-specific integrated circuit(ASIC), other chipset, logic circuit and/or data processing device. Thememory may include read-only memory (ROM), random access memory (RAM),flash memory, memory card, storage medium and/or other storage device.The RF unit may include baseband circuitry to process radio frequencysignals. When the embodiments are implemented in software, thetechniques described herein can be implemented with modules (e.g.,procedures, functions, and so on) that perform the functions describedherein. The modules can be stored in the memory and executed byprocessor. The memory can be implemented within the processor orexternal to the processor in which case those can be communicativelycoupled to the processor via various means as is known in the art.

In view of the exemplary systems described herein, methodologies thatmay be implemented in accordance with the disclosed subject matter havebeen described with reference to several flow diagrams. While forpurposed of simplicity, the methodologies are shown and described as aseries of steps or blocks, it is to be understood and appreciated thatthe claimed subject matter is not limited by the order of the steps orblocks, as some steps may occur in different orders or concurrently withother steps from what is depicted and described herein. Moreover, oneskilled in the art would understand that the steps illustrated in theflow diagram are not exclusive and other steps may be included or one ormore of the steps in the example flow diagram may be deleted withoutaffecting the scope and spirit of the present disclosure.

What is claimed is:
 1. A method for receiving data in a wirelesscommunication system, the method comprising: receiving, by a wirelessdevice, expansion subframe information indicating at least one expansionsubframe in which expansion modulation scheme is supported among aplurality of subframes; receiving, by the wireless device, downlinkcontrol information that includes a modulation and coding scheme (MCS)field indicating the expansion modulation scheme on a downlink controlchannel, in the at least one expansion subframe; and receiving, by thewireless device, downlink data on a downlink shared channel according tothe downlink control information.
 2. The method of claim 1, wherein theexpansion subframe supports a modulation scheme that has modulationorder of 8, and non-expansion subframe, which is not the expansionsubframe among the plurality of subframes, has a modulation order ofless than
 8. 3. The method of claim 1, wherein the expansion modulationscheme includes 256-quadrature amplitude modulation (QAM).
 4. The methodof claim 2, wherein the MCS field has different bit numbers in theexpansion subframe and the non-expansion subframe.
 5. The method ofclaim 2, wherein the MCS field has a same bit number in the expansionsubframe and the non-expansion subframe.
 6. The method of claim 5,wherein MCS tables for the MCS field are different in the expansionsubframe and the non-expansion subframe.
 7. The method of claim 1,wherein the expansion subframe information includes information on aplurality of expansion frame sets, and wherein MCS table is defined foreach of the plurality of expansion frame sets.
 8. The method of claim 7,wherein at least one of a plurality of MCS tables for the plurality ofexpansion frame sets is an expansion MCS table including the expansionmodulation scheme, and wherein a channel quality indicator (CQI) tablerelated to the expansion MCS table includes the expansion modulationscheme.
 9. A wireless device in a wireless communication system, thewireless device comprising: a radio frequency (RF) unit configured totransmit and receive a radio signal; and a processor connected to the RFunit, wherein the processor is configured to: receive expansion subframeinformation indicating at least one expansion subframe in whichexpansion modulation scheme is supported among a plurality of subframesthrough the RF unit; receive downlink control information that includesa modulation and coding scheme (MCS) field indicating the expansionmodulation scheme on a downlink control channel, in the at least oneexpansion subframe through the RF unit; and receive downlink data on adownlink shared channel according to the downlink control informationthrough the RF unit.
 10. The wireless device of claim 9, wherein theexpansion subframe supports a modulation scheme that has modulationorder of 8, and non-expansion subframe, which is not the expansionsubframe among the plurality of subframes, has a modulation order ofless than
 8. 11. The wireless device of claim 9, wherein the expansionmodulation scheme includes 256-quadrature amplitude modulation (QAM).